1. Field of the Invention
The invention relates to a query unit for determining the status of moving or movable parts of a system part, particularly for determining the end positions of a clamping arm of a toggle lever clamping apparatus, having a sensor unit and an electroblock. The sensor unit has at least one sensor and a connector plug-in connection part for connecting the sensor unit with the electroblock and can be attached to the system part. The electroblock has at least one electrical connector element for connecting an outer, releasable connection cable, a connector plug-in connection part for connecting the electroblock with the sensor unit, and at least one screw passage opening for installation on an outer surface of the system part.
Furthermore, the invention relates to a toggle lever clamping apparatus having such a query unit.
2. Description of the Related Art
Toggle lever clamping apparatuses are used in car body construction to hold components in sheet-metal form, for example in order to then permanently connect these by means of spot welding, gluing, clinching or the like. High holding and pressing forces achieved using the toggle lever joint allow secure fixation. In general, such toggle lever clamping apparatuses consist of a clamping head and a piston/cylinder unit that follows this head axially, the unit consisting of a cylinder and a piston to which the pressure of a pressure medium, particularly compressed air, is alternately applied on both sides. The piston is provided with a piston rod that passes through the clamping head, in part, and carries the toggle lever joint arrangement at the end, by way of a joint. The toggle lever joint arrangement is connected with a clamping arm that interacts with a jaw or the like, in such a manner that the components to be held can be clamped in place between the jaw and the clamping arm. In general, such toggle lever clamping apparatuses are incorporated into a sequencing control, so that the production lines can be automated, to a great extent.
Such a clamping apparatus is known, for example, from EP 0 938 952 A2. The clamping apparatus described therein has a head piece having a clamping arm mounted on it so as to pivot, which arm is connected with a drive element by way of a setting mechanism disposed in the head piece. The setting mechanism has a positioner that is adjustable along a setting path. A coil to which current can be applied is disposed along the setting path for querying the position, so that the positioner is situated in the gradient-oriented region of effect of the magnetic field of the coil in all positions of the setting mechanism. In this way, every position of the clamping arm can be queried at all times.
If the query is directed only at end positions, clearly the structure can be simplified. For example, a sensor unit for a clamping apparatus is known from DE 296 14 630 U1, which unit determines only the movement end positions. For this purpose, the sensor unit has two sensors that can be attached in the housing of the clamping apparatus, which sensors are connected with a connector and display housing having a connector plug-in connection part, by means of connection cables. The connector and display housing has two intersecting screw passage openings and can be attached to the clamping apparatus in one of two different installation positions, by means of an attachment screw that passes through one of these screw passage openings. Furthermore, the clamping apparatus has an installation plate having two thresholds, which form an insertion shaft for the connector and display housing.
It is furthermore known from DE 203 15 012 U1, that a connection between a connector and display housing, which is referred to as an electroblock, and electrical sensor satellites can be configured not only in wired manner but also in wireless manner.